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| author | Peter Zijlstra <peterz@infradead.org> | 2021-08-26 09:36:53 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2021-08-27 14:28:49 +0200 |
| commit | 6467822b8cc96e5feda98c7bf5c6329c6a896c91 (patch) | |
| tree | e48f49c0c44f69ee2ea93b98e18d17bc5ea1c17d /include/linux/sched | |
| parent | 37e8abff2bebbf9947d6b784f5c75ed48a717089 (diff) | |
locking/rtmutex: Prevent spurious EDEADLK return caused by ww_mutexes
rtmutex based ww_mutexes can legitimately create a cycle in the lock graph
which can be observed by a blocker which didn't cause the problem:
P1: A, ww_A, ww_B
P2: ww_B, ww_A
P3: A
P3 might therefore be trapped in the ww_mutex induced cycle and run into
the lock depth limitation of rt_mutex_adjust_prio_chain() which returns
-EDEADLK to the caller.
Disable the deadlock detection walk when the chain walk observes a
ww_mutex to prevent this looping.
[ tglx: Split it apart and added changelog ]
Reported-by: Sebastian Siewior <bigeasy@linutronix.de>
Fixes: add461325ec5 ("locking/rtmutex: Extend the rtmutex core to support ww_mutex")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/YSeWjCHoK4v5OcOt@hirez.programming.kicks-ass.net
Diffstat (limited to 'include/linux/sched')
0 files changed, 0 insertions, 0 deletions